Potent Multidrug Resistance Reversal Agent Research Articles

Nobiletin and its derivatives overcome multidrug resistance (MDR) in cancer: total synthesis and discovery of potent MDR reversal agents

Our recent studies demonstrated that the natural product nobiletin (NOB) served as a promising multidrug resistance (MDR) reversal agent and improved the effectiveness of cancer chemotherapy in vitro. However, low aqueous solubility and difficulty in total synthesis limited its application as a therapeutic agent. To tackle these challenges, NOB was synthesized in a high yield by a concise route of six steps and fourteen derivatives were synthesized with remarkable solubility and efficacy. All the compounds showed improved sensitivity to paclitaxel (PTX) in P-glycoprotein (P-gp) overexpressing MDR cancer cells. Among them, compound 29d exhibited water solubility 280-fold higher than NOB. A drug-resistance A549/T xenograft model showed that 29d, at a dose of 50 mg/kg co-administered with PTX (15 mg/kg), inhibited tumor growth more effective than NOB and remarkably increased PTX concentration in the tumors via P-gp inhibition. Moreover, Western blot experiments revealed that 29d inhibited expression of NRF2, phosphorylated ERK and AKT in MDR cancer cells, thus implying 29d of multiple mechanisms to reverse MDR in lung cancer.

H6, a novel hederagenin derivative, reverses multidrug resistance in vitro and in vivo

Multidrug resistance (MDR) is a serious obstacle encountered in cancer treatment, in which the overexpression of P-glycoprotein (P-gp) plays an important role. Here, a novel α-hederagenin derivative, designated H6, was designed, synthesized and evaluated for its ability to reverse MDR. Our results showed that H6 could sensitize KBV and MCF7/T cells to paclitaxel and vincristine. Meanwhile, H6 could increase both rhodamine 123 and paclitaxel accumulation in MDR cells without affecting the expression of P-gp. Interestingly, siRNA knockdown of MDR1 further sensitized the cytotoxic activity of paclitaxel when co-administrated with H6. In addition, H6 could directly stimulate P-gp ATPase activity in vitro. Importantly, H6 enhanced the efficacy of paclitaxel against KBV cancer cell-derived xenograft tumors in nude mice. Finally, H6 showed high binding affinity with P-gp with a high docking score. Overall, we show H6 is a novel and potent MDR reversal agent, which has the potential to be administered in combination with conventional anticancer drugs.

Co-encapsulation of paclitaxel and baicalein in nanoemulsions to overcome multidrug resistance via oxidative stress augmentation and P-glycoprotein inhibition

Multidrug resistance (MDR) is a major obstacle for clinical application of paclitaxel (PTX). Recent studies have suggested that baicalein (BA) might be a potent MDR reversal agent with the ability of P-glycoprotein inhibition and oxidative stress augmentation. Herein, we co-encapsulated PTX and BA in nanoemulsions (PTX/BA NE) for overcoming MDR in breast cancer. Paclitaxel-cholesterol complex and baicalein-phospholipid complex were prepared to improve the liposolubility of PTX and BA. The cytotoxicity of the combination of PTX and BA with different weight ratios were evaluated and the combination with a weight ratio of 1/1 exhibited the strongest synergistic effect. In vitro cytotoxicity study indicated that PTX/BA NE had a better antitumor efficacy in MCF-7/Tax cells than other PTX formulations. Studies on cellular uptake demonstrated that the PTX/BA NE could effectively accumulate in cancer cells. Mechanism research showed that PTX/BA NE could significantly increase the cellular reactive oxygen species (ROS), decrease cellular glutathione (GSH), and enhance caspase-3 activity in MCF-7/Tax cells. More importantly, in vivo antitumor study demonstrated that PTX/BA NE exhibited a much higher antitumor efficacy than other PTX formulations. These findings suggest that co-delivery of PTX and BA in nanoemulsions might provide us a potential combined therapeutic strategy for overcoming MDR.

Abstract 762: Prevention and reversion of multidrug resistance (MDR) in cancer by NSC23925

Abstract The major limitation to the success of chemotherapy in cancer is the development of multidrug resistance (MDR). Preventing the emergence of MDR during chemotherapy treatment has been a high priority of clinical and investigational oncology, but remains an elusive goal. NSC23925 has recently been identified as a novel and potent MDR reversal agent. However, whether NSC23925 can prevent the development of MDR in cancer is unknown. Therefore, this study was to evaluate the effects of NSC23925 on prevention and reversion of MDR. Human osteosarcoma cell line U-2OS and Saos were exposed to increasing concentrations of taxol alone or in combination with NSC23925 for 6 months. The results showed that cells selected with increasing concentrations of taxol alone developed MDR with resistance to taxol and other Pgp substrates, while cells cultured with taxol-NSC23925 simultaneously prevented the development of MDR and cells remained sensitive to chemotherapeutic agents. Taxol selected resistant cells showed high expression and activity of drug transporter P-glycoprotein (Pgp), whereas taxol-NSC23925 combination treatment prevented the expression of Pgp. Our findings suggest that NSC23925 may prevent the development of MDR by specifically preventing the overexpression of Pgp. Moreover, NSC23925 can reverse MDR in drug resistant cells by modulating Pgp activity. Given the significant incidence of MDR in cancer and the lack of effective agents for prevention and revision of MDR, NSC23925 and derivatives hold the potential to improve the outcome of cancer patients with poor prognosis due to drug resistance. Citation Format: Xiaoqian Yang, Francis Hornicek, Zhenfeng Duan. Prevention and reversion of multidrug resistance (MDR) in cancer by NSC23925. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 762. doi:10.1158/1538-7445.AM2014-762

In Vivo Evaluation of Eclipta alba Extract as Anticancer and Multidrug Resistance Reversal Agent

The present study investigates the anticancer and multidrug resistance (MDR) reversal potential of hydro-alcoholic Eclipta alba extract (EAE) through in vivo experiments. Diethylnitrosamine (DEN) and 2-acetylaminofluorene (AAF) were used for liver cancer induction in animal model, whereas for MDR induction, AAF was used. The level of antioxidant enzymes was studied in serum along with biochemical parameters. Cancer and MDR-induced liver cells have higher levels of reactive oxygen species (ROS) and, in turn, are responsible for the maintenance of the cancer phenotype. Treatment with EAE declines the ROS level and revealed the ROS scavenging properties. Alfa feto protein levels were found to increase significantly in cancer-induced animals confirming induction and progression of liver cancer, EAE treatment was found to bring back the altered levels within normal range indicating the therapeutic effect of plant extract over liver cancer. Zymogram showed the inhibition of MMPs and RT-PCR analysis revealed that the mRNA expression of nuclear factor-kB was markedly decreased upon EAE treatment. Further, our results showed that EAE could significantly inhibit mdr1 gene encode P-glycoprotein expression. Our data suggest that EAE is a novel anticancer and potent MDR reversal agent and may be a potential adjunctive agent for tumor chemotherapy.

Prevention of multidrug resistance (MDR) in osteosarcoma by NSC23925

Background:The major limitation to the success of chemotherapy in osteosarcoma is the development of multidrug resistance (MDR). Preventing the emergence of MDR during chemotherapy treatment has been a high priority of clinical and investigational oncology, but it remains an elusive goal. The NSC23925 has recently been identified as a novel and potent MDR reversal agent. However, whether NSC23925 can prevent the development of MDR in cancer is unknown. Therefore, this study aims to evaluate the effects of NSC23925 on prevention of the development of MDR in osteosarcoma.Methods:Human osteosarcoma cell lines U-2OS and Saos were exposed to increasing concentrations of paclitaxel alone or in combination with NSC23925 for 6 months. Cell sublines selected at different time points were evaluated for their drug sensitivity, drug transporter P-glycoprotein (Pgp) expression and activity.Results:We observed that tumour cells selected with increasing concentrations of paclitaxel alone developed MDR with resistance to paclitaxel and other Pgp substrates, whereas cells cultured with paclitaxel–NSC23925 did not develop MDR and cells remained sensitive to chemotherapeutic agents. Paclitaxel-resistant cells showed high expression and activity of the Pgp, whereas paclitaxel–NSC23925-treated cells did not express Pgp. No changes in IC50 and Pgp expression and activity were observed in cells grown with the NSC23925 alone.Conclusions:Our findings suggest that NSC23925 may prevent the development of MDR by specifically preventing the overexpression of Pgp. Given the significant incidence of MDR in osteosarcoma and the lack of effective agents for prevention of MDR, NSC23925 and derivatives hold the potential to improve the outcome of cancer patients with poor prognosis due to drug resistance.

Icaritin reverses multidrug resistance of HepG2/ADR human hepatoma cells via downregulation of MDR1 and P-glycoprotein expression

Multidrug resistance (MDR) of tumor cells is a serious obstacle encountered in cancer treatment. In the current study a multiple drug‑resistant HepG2/adriamycin (HepG2/ADR) cell line was established and its MDR was characterized. Icaritin, an active ingredient isolated from the medical plant Herba Epimedium, was observed to reverse MDR in the present model. Icaritin significantly increased the intracellular accumulation of ADR and decreased the expression of the MDR1 gene in HepG2/ADR cells compared with drug‑sensitive HepG2 cells. In addition, the present results showed that icaritin may significantly downregulate the expression of P‑glycoprotein. These results indicate that icaritin is a novel and potent MDR reversal agent and may be a promising drug for tumor chemotherapy.

Reversion of P-glycoprotein-mediated multidrug resistance by guggulsterone in multidrug-resistant human cancer cell lines

Multidrug resistance (MDR) presents a serious problem in cancer chemotherapy. Our previous studies have shown that guggulsterone could reverse MDR through inhibiting the function and expression of P-glycoprotein (P-gp). The present study is to further investigate the reversal effects of guggulsterone on MDR in drug-resistant cancer cell lines. The effects of guggulsterone on MDR1mRNA gene expression, intracellular pH, P-gp ATPase activity and glucosylceramide synthase (GCS) expression were assessed by RT-PCR, Laser Scanning Confocal Microscope using the pH-sensitive fluorescent probe BCECF-AM, Pgp-Glo assay system, and flow cytometric technology, respectively. The results showed that guggulsterone ranging from 2.5 to 80μM significantly promoted the activity of P-gp ATPase in a dose-dependent manner. The intracellular pH of K562/DOX cells was found to be higher than K562 cells. After treatment with guggulsterone (1, 3, 10, 30, 100μM), intracellular pH of K562/DOX cells decreased in a dose- and time-dependent manner. However, the present study revealed that guggulsterone ranging from 3 to 100μM had little influence on MDR1 gene expression in K562/DOX cells. Further, the isogenic doxorubicin-resistant MCF-7/DOX cells exhibited a 4.9-fold increase in GCS level as compared with parental MCF-7 human breast cancer cells. After treatment with guggulsterone (0.1, 1, 10μM) for 48h, MCF-7/DOX cells were found to have no change of GCS protein expression amount. Guggulsterone might be a potent MDR reversal agent, and its mechanism on MDR needs more research.

Reversal of P-glycoprotein-mediated multidrug resistance of human hepatic cancer cells by Astragaloside II

Chemoresistance is the main obstacle encountered in cancer treatment and is frequently associated with multidrug resistance (MDR). Astragaloside is a saponin which is widely used in traditional Chinese medicine. It has been reported that Astragaloside has antitumour effects on hepatocellular carcinoma Bel-7402 cells in vitro and in vivo. The purpose of this study was to examine the effects of Astragaloside II on the reversal of MDR and its molecular mechanism in vitro. In this study, Bel-7402 and Bel-7402/FU cell lines were used as the experimental model. Drug sensitivity was determined using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, accumulation and efflux of Rh123 were analyzed by flow cytometer, the mRNA level of mdr1 was determined by RT-PCR and the protein levels of P-glycoprotein (P-gp) and mitogen-activated protein kinase were determined by Western blot. Astragaloside II (0.08 mg/ml) showed strong potency to increase 5-fluorouracil cytotoxicity toward 5-fluorouracil-resistant human hepatic cancer cells Bel-7402/FU. The mechanism of Astragaloside II on P-gp-mediated MDR demonstrated that Astragaloside II significantly increased the intracellular accumulation of rhodamine 123 via inhibition of P-gp transport function. Based on the analysis of P-gp and mdr1 gene expression using Western blot and RT-PCR, the results revealed that Astragaloside II could downregulate the expression of the P-gp and mdr1 gene. In addition, Astragaloside II suppressed phosphorylation of extracellular signal regulated kinase 1/2, p38 and c-Jun N-terminal kinase. The results suggested that Astragaloside II is a potent MDR reversal agent and may be a potential adjunctive agent for hepatic cancer chemotherapy.

Synthesis and Bioactivity of Novel Adamantyl Derivatives as Potent MDR Reversal Agents

Multidrug Resistance (MDR) is a type of resistance of tumor cells to various kinds of chemotherapeutic drugs which are structurally unrelated and also one of the major impediments to chemotherapeutic treatment of cancer. It has been reported that 49 ATP-binding cassette (ABC) transporter genes are present in the human genome. Among them, over-expression of P-glycoprotein (P-gp), encoded by MDR1 gene is one of the major factors contributing to multidrug resistance which leads to barrier to successful chemotherapy. Therefore the availability of safe and potent MDR reversal agents would be beneficial for clinical use. Reversal agents can act by binding to the membrane transport protein (P-gp), by inhibiting MDR’s drug efflux capacity, or by suppressing expression of the MDR1 gene itself. Although a number of P-gp inhibitors have been developed, there is currently no clinically useful drug that inhibits P-gp. In an attempt to find new and more effective MDR reversal agents, we previously identified adamantyl derivatives exhibiting more potent MDR reversal activity than verapamil, a well-known P-gp inhibitor, without considerable intrinsic cytotoxicity. Compounds 1-2 were identified utilizing high throughput image-based DIOC2 efflux assays and anti-proliferation assays in a P-gp over-expressing MDR sarcoma cell line, MES-SA/DX5. Herein we describe a further structure-activity relationship study to find additional compounds in this series. With the objective of investigating the effect of aminebased substituents on reversal activity, we synthesized a series of adamantyl derivatives 2a-t that feature reductive amination of the adamantyl aldehyde derivatives as a key step. The synthetic procedures for 2a-t are described in Schemes 1 to 3. Synthesis of a new series of adamantyl derivatives (2a-t) were carried out starting from commercially available 3amino benzoic acid 3 (Scheme 1). The corresponding esters (4a-d) and amides (4e-g) of 3-amino benzoic acid were prepared in the next step. Further alkylation with chloroacetyl chloride resulted in the alkylated derivatives (5a-g). Bromination of 1-adamantane carboxylic acid 6 with bromine gave an intermediate 7, which was followed by Friedel-Crafts alkylation with anisole to provide compound 8, as shown in Scheme 2. Esterification of 8 resulted in compound 9, which was reacted with LiAlH4 to give an alcohol 10. The aldehyde 11 was then obtained by oxidation of alcohol 10. Demethylation of 11 was carried out by using BBr3 to afford a phenol compound 12, which was utilized as a key intermediate to prepare the final compounds. Adamantyl aldehyde 13, a precursor for the synthesis of the target adamantyl motifs (2a-n), was generated by reacting 12 with methyl 3-(2chloroacetamido) benzoate 5a. In similar fashion, the precursor 14o-t was generated by reacting 12 with 5b-g for the synthesis of derivatives 2o-t. Finally the reductive amination reaction of 13 or 14o-t with a variety of amine resulted in Pgp related MDR modulators 2a-t. Reversal activity of these derivatives was evaluated in

Reversal of Multidrug Resistance by Guggulsterone in Drug-Resistant MCF-7 Cell Lines

Background: Multidrug resistance (MDR) presents a serious problem in cancer chemotherapy. Our previous studies have shown that the MDR of K562/DOX cells could be reversed by guggulsterone through inhibiting the function and expression of P-glycoprotein. The purpose of this study was to investigate the reversal effect of guggulsterone on MDR in drug-resistant MCF-7 cells and the parental MCF-7 cells. Methods: MTT cytotoxicity assays, flow cytometry, and Western blot analysis were performed to investigate the antiproliferative effects of the combination of anticancer drugs with guggulsterone, to study the reversal of drug resistance and to examine the inhibitory effects on MRP1 expression. Results: The results showed that co-administration of guggulsterone (10 µM) resulted in a significant increase in chemosensitivity of MCF-7/DOX cells to doxorubicin, compared with doxorubicin treatment alone (p < 0.01). The fold reversal of 10 µM guggulsterone (11.48) was comparable to that of 10 µM verapamil (13.23). Rhodamine123 and doxorubicin accumulation in MCF-7/DOX cells was significantly enhanced after the incubation with guggulsterone (10 µM), compared with untreated MCF-7/DOX cells (p < 0.01). When doxorubicin (10 µM) was combined with guggulsterone (10 µM), the mean apoptotic population of MCF-7/DOX cells was 24.91%. It was increased by 6.15 times, compared with doxorubicin (10 µM) treatment alone. However, guggulsterone had little inhibitory effect on the expression of MRP1 proteins. Conclusion: Guggulsterone is a novel and potent MDR reversal agent with the potential to be an adjunctive agent for tumor chemotherapy.

Reversal effect of Dioscin on multidrug resistance in human hepatoma HepG2/adriamycin cells

Multidrug resistance is a serious obstacle encountered in cancer treatment. Since drug resistance in human cancer is mainly associated with overexpression of the multidrug resistance gene 1 (MDR1), the promoter of the human MDR1 gene may be a target for multidrug resistance reversion drug screening. In the present study, HEK293T cells were transfected with pGL3 reporter plasmids containing the 2kb of MDR1 promoter, and the transfected cells were used as models to screen for candidate multidrug resistance inhibitors from over 300 purified naturally occurring compounds extracted from plants and animals. Dioscin was found to have an inhibiting effect on MDR1 promoter activity. The resistant HepG2 cell line (HepG2/adriamycin) was used to validate the activity of multidrug resistance reversal by Dioscin. Results showed that Dioscin could decrease the resistance degree of HepG2/adriamycin cells, and significantly inhibit P-glycoprotein expression, as well as increase the accumulation of adriamycin in HepG2/adriamycin cells as measured by Flow Cytometric analysis. These results suggest that Dioscin is a potent multidrug resistance reversal agent and may be a potential adjunctive agent for tumor chemotherapy.

ChemInform Abstract: A Novel Class of Highly Potent Multidrug Resistance Reversal Agents: Disubstituted Adamantyl Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A novel class of highly potent multidrug resistance reversal agents: Disubstituted adamantyl derivatives

Novel disubstituted adamantyl derivatives were synthesized and evaluated in a P-glycoprotein dependent multidrug resistance cancer cell line. The hit to lead optimization provided potent MDR reversal agents. Some potent adamantyl derivatives were more than 10-fold more potent than verapamil without considerable intrinsic cytotoxicity. The 3-trifluorophenyl derivative 14f did not affect the metabolism of CYP450 3A4, whereas most of MDR revertants had a weak inhibitory effect.

Synthesis and multidrug resistance reversal activity of dihydroptychantol A and its novel derivatives

The macrocyclic bisbibenzyl dihydroptychantol A (DHA), previously isolated from Asterella angusta, was synthesized and showed significant multidrug resistance (MDR) reverting activity in chemoresistant cancer cells. In an attempt to discover more potent MDR reversal agents for efficient cancer chemotherapy, DHA derivatives with thiazole rings ( 19– 22) were synthesized, and their cytotoxicities and MDR reversal activities were evaluated in adriamycin-resistant K562/A02, vincristine-resistant KB/VCR and in their parental cells by MTT assays. In response to treatment with each compound, the K562 cell line was the most sensitive, and the vincristine-resistant KB/VCR cell line was the most resistant. Marked decreases in K562 and K562/A02 cell viability were detectable after treatment with the synthesized derivatives of DHA, while less inhibitory effects on cell growth were observed in chemical-resistant KB/VCR and KB cells. Moreover, among the tested compounds, the intermediate 17 and the analogues 19, 20, and 21 showed potent MDR reversal activities and increased vincristine cytotoxicity in KB/VCR cells, with the reversal fold ranges from 10.54 to 13.81 (10 μM), which is 3.2–4.3-fold stronger than the natural product DHA.

Cantharidin reverses multidrug resistance of human hepatoma HepG2/ADM cells via down-regulation of P-glycoprotein expression

Multidrug resistance (MDR) is a serious obstacle encountered in cancer treatment. In this study, we established an in vitro multiple drug resistant HepG2 cell line (HepG2/ADM), and characterized its MDR. This model was used to screen potential candidate chemosensitisers from over 200 purified naturally occurring compounds extracted from plants and animals. Cantharidin was found to have a significant reversal on MDR in our model. Further, our results showed that Cantharidin could significantly inhibit P-gp (P-glycoprotein) expression, mRNA transcription, as well as MDR1 promoter activity. These results suggest that Cantharidin is a novel and potent MDR reversal agent and may be a potential adjunctive agent for tumor chemotherapy.

Reversal of P-Glycoprotein Mediated Multidrug Resistance in K562 Cell Line by a Novel Synthetic Calmodulin Inhibitor, E6

The overexpression of P-glycoprotein (P-gp) is associated with multidrug resistance (MDR) of tumor cells to a number of chemotherapeutic drugs. P-gp inhibitors have been shown to effectively reverse P-gp-mediated MDR in both in vitro and in vivo. Our previous studies demonstrated that E6, a novel synthetic calmodulin inhibitor, exhibited potent inhibitory effect on P-gp in rat brain microvessel endothelial cells (RBMECs). In the present study, the effect of E6 on MDR in a K562 MDR cell line (K562/DOX) highly expressing P-gp was studied and compared with that of a conventional P-gp inhibitor, verapamil (VER). E6 at concentrations of 1, 3, 10, 30 microM reduced the IC50 value of doxorubicin in K562/DOX cells from 79.19 microM to 35.18, 21.86, 6.31 and 1.97 microM, respectively. However, the IC50 value of doxorubicin in K562 sensitive subline was not significantly changed by E6. Using a DNA content analysis and an annexin V binding assay, the effects of E6 on doxorubicin-induced apoptosis were also examined. The results indicated that E6 effectively reversed the resistance to doxorubicin-induced apoptosis in K562/DOX cells. In addition, co-treatment of E6 and doxorubicin resulted in a remarkably G2/M blocking effect in K562/DOX cells. Furthermore, the treatment of K562/DOX cells with 10 microM E6 led to increased intracellular accumulation and decreased efflux of doxorubicin. Overall, the pharmacological effects of E6 on P-gp-mediated MDR is much stronger than that of positive control drug VER. These results suggested that E6 is a novel and potent MDR reversal agent and may be a potential adjunctive agent for tumor chemotherapy.

Multidrug resistance reversal activity of key ningalin analogues.

Key analogue derivatives of the ningalins, potent multidrug resistance (MDR) reversal compounds, were examined resulting in the discovery of a potent MDR reversal agent that hypersensitizes P-gp resistant tumor cell lines to front-line conventional therapeutic agents.